Medical Bulletin 18/ July/ 2024

In a study recently published in the renowned journal "Allergy", a MedUni Vienna research team showed that COVID-19 leads to considerable long-term changes in the immune system, even in mild cases.

COVID-19, caused by the SARS-CoV-2 virus, significantly impacts the body's immune system. Even after mild cases, the virus can lead to a lasting reduction in immune cells and a drop in specific antibodies. This weakens the immune system's ability to respond to new infections. Additionally, changes in cytokines and growth factors indicate a lingering inflammatory response. These effects suggest that COVID-19 can cause long-term immune system impairments, potentially contributing to prolonged health issues such as Long-COVID.

In the study, researchers looked at important immune markers in 133 people who had recovered from COVID-19 and 98 people who had never had the virus. They analyzed the number and types of various immune cells, as well as cytokines and growth factors in the blood, which are crucial for regulating cell growth. The recovered patients were tested ten weeks and ten months after their initial infection. Since there were no COVID-19 vaccines available in 2020 during the study period, all participants remained unvaccinated. This allowed the researchers to examine the long-term effects of the SARS-CoV-2 infection without any influence from vaccines.

The study also found that cytokines and growth factors in the blood of recovered patients were typical of those seen after an acute inflammatory process. When comparing samples from patients taken ten months after recovering from COVID-19, researchers noticed an unexpected pattern. Even after mild cases, there was a significant reduction of immune cells in the blood.

Additionally, there was a notable drop in SARS-CoV-2-specific antibodies and a surprising change in growth factor patterns in the blood.

This suggested that the immune systems of those who had COVID-19 might not respond as effectively to new challenges, possibly explaining some long-term effects of the virus, such as Long-COVID. Researchers believe that these long-term impacts are likely due to the infection causing prolonged impairment of the bone marrow, which is crucial for producing immune cells.

Reference: Kratzer, B., et al. (2024) Differential decline of SARS-CoV-2-specific antibody levels, innate and adaptive immune cells, and shift of Th1/inflammatory to Th2 serum cytokine levels long after first COVID-19. Allergy. doi.org/10.1111/all.16210.

A longitudinal study by University of Queensland researchers has found high-intensity interval exercise improves brain function in older adults for up to 5 years.

Th research was published in the journal Aging and Disease.

High-intensity interval training (HIIT) benefits older adults by significantly improving cognitive function. This exercise method, involving short bursts of intense activity, enhances brain health more effectively than moderate or low-intensity workouts. Incorporating HIIT into regular routines helps maintain and boost cognitive abilities, promoting better overall brain function in seniors.

For the study, researchers evaluated the impact of three exercise intensities on cognitive function in older adults:

Low intensity: Focused on motor function, balance, and stretching

Medium intensity: Involved brisk walking on a treadmill

High intensity: Consisted of four cycles of running on a treadmill at near maximum exertion

The result showed that high-intensity interval exercise led to cognitive improvements that persisted for up to five years. High-resolution MRI scans of participants in this group showed structural and connectivity changes in the hippocampus, the brain area responsible for learning and memory. Additionally, blood biomarkers correlated with cognitive improvements, indicating their potential use in predicting the effectiveness of the exercise regimen.

Given that one in three people aged 85 years or older is likely to develop dementia, these findings have significant implications. The results could inform exercise guidelines for older adults, and future research could explore different types of exercise suitable for aged care. The study also highlighted the need to investigate genetic factors that may influence an individual's response to exercise and the potential use of biomarkers as a diagnostic tool for exercise efficacy.

“Six months of high-intensity interval training is enough to flick the switch. In earlier pre-clinical work, we discovered exercise can activate stem cells and increase the production of neurons in the hippocampus, improving cognition. In this study, a large cohort of healthy 65 – 85-year-old volunteers joined a six-month exercise program, did biomarker and cognition testing and had high-resolution brain scans. We followed up with them 5 years after the program and incredibly they still had improved cognition, even if they hadn't kept up with the exercises,” said Emeritus Professor Perry Bartlet.

Reference: Blackmore, D. G., et al. (2024) Long-Term Improvement in Hippocampal-Dependent Learning Ability in Healthy, Aged Individuals Following High Intensity Interval Training. Aging and Disease. doi.org/10.14336/AD.2024.0642.

A new study conducted by the American Cancer Society, published in the journal CA: A Cancer Journal for Clinicians, suggested that substantial reductions in cancer cases and deaths could be achieved through lifestyle changes. The study highlighted the importance of maintaining a healthy body weight, limiting alcohol consumption, eating a healthy diet, and being physically active.

For the study, researchers examined data from 2019, focusing on 30 types of cancer and 18 modifiable risk factors such as smoking and body weight. Among these, cigarette smoking was identified as the leading risk factor, contributing to nearly 20% of all cancer cases and 30% of all cancer deaths. The study found that lifestyle factors were linked to more than 700,000 new cancer cases and over 262,000 deaths among adults aged 30 and older.

The study identified the top ten risk factors for cancer, which include:

Smoking: Cigarette smoking remains the leading contributor to cancer cases and deaths in both men and women. Despite being a modifiable risk factor, the uptake of recommended lung cancer screenings among high-risk individuals remains low.

Bodyweight: Excess body weight was responsible for nearly 7%–8% of all cancer cases and deaths in the United States. Maintaining a healthy body weight is crucial for cancer prevention.

Alcohol Use: Alcohol consumption contributed to 5.4% of cancer cases in men and 4.1% in women. Limiting alcohol intake can significantly reduce cancer risk.

Poor Diet: Low fruit and vegetable consumption was a major dietary factor contributing to cancer cases and deaths. A healthy diet rich in fruits and vegetables is essential for reducing cancer risk.

Lack of Exercise: Physical inactivity, combined with excess body weight, alcohol consumption, and poor diet, contributed to a significant proportion of cancer cases, particularly in women.

Missing Cancer Screenings: The suspension of cancer screenings, especially during the 2020 coronavirus pandemic, led to increased cancer cases due to disruptions in employment, health insurance, and fear of COVID-19.

Sun Exposure: Nearly 93% of all skin melanoma cases and deaths in the United States are attributable to UV radiation. Protective measures such as limiting sun exposure, wearing protective clothing, and using broad-spectrum sunscreen are recommended.

Infections: HPV infection was the largest contributor to cancer cases (1.8%) and deaths (1.2%) attributable to any carcinogenic infection evaluated in this study.

In conclusion, by addressing the risk factors, 40% of cancer cases and deaths could be prevented.

Reference: Farhad Islami MD, PhD, Emily C. Marlow PhD, Blake Thomson DPhil, MPhil, Marjorie L. McCullough ScD, RD, Harriet Rumgay PhD; Proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors in the United States, 2019; 11 July 2024; CA: A Cancer Journal for Clinicians; https://doi.org/10.3322/caac.21858